A wireless telecommunication system typically includes a plurality of base stations connected to a communication network. Each base station includes radio transceivers associated with a transmission tower. A typical base station includes one or more filters for processing IF signals. One such filter is known as a microwave cavity filter which includes resonators formed in cavities in order to provide a desired frequency response when signals are input to the filter.
One type of cavity filter design employs dual-mode resonators utilized in the cavity filters, providing desired filter functions while reducing the filter size compared to conventional cavity filters utilizing single mode resonators. However, many existing dual-mode resonators are difficult to manufacture due to the shape of the resonator structure. Other existing resonators that use hybrid modes, are too large and bulky for certain applications.
Accordingly, an objective of the present invention is to provide a structure for smaller base station cavity filters which avoids the above-noted problems.